The advent of recombinant DNA techniques has resulted in the description of a variety of new categories of genetic markers for our species, in quantities that far exceed the genetic information that previously could be defined by serological and electrophoretic means. Because the techniques used to define these markers are so new, the implications of these new types of genetic markers for human population genetics are only just being perceived. These new markers have revolutionized the study of linkage relationships in Man, and other species, leading to the successful construction of a skeleton linkage map for the entire genome, in just a few years. While the impact of these new markers on human population genetics is likely to be equally profound, so far there have been relatively few attempts to characterize the distribution of the different categories of markers within human populations. We propose to use four distinct categories of DNA polymorphisms to attain to follcwing two scientific objectives: a) To gain insight into the genetic structure of eight different North American Indian tribal populations and evaluate the genetic relationships between them. b) Evaluate theoretical models that characterize the evolutionary distribution of different types of DNA polymorphism over relatively short time scales (< 600 generations, or less). The four categories of DNA polymorphism that will be evaluated include i) single site RFLP's; ii) single locus haplotypes; iii) extensively polymorphic VNTR's; iv) uniparentally transmitted polymorphic (mitochondrial DNA and RFLP's from non pairing regions of the Y chromosome). Each of the eight tribes will be represented by a sample of 75 mother-father-child trios (225 people in all) and the resulting data will be analyzed by traditional methods in population genetics, as well as being used to evaluate new models for the evolutionary distribution of these genetic markers in relatively small human populations.